the path for resized images was missing a slash, view description

Missing the tmp/ slash, trying to write the image in the theme's root. 

Something like:

/var/www/wordpress/wp-content/themes/theme-name/tmpb0a1f733d586f7cdb7f47381a6b5efd6.jpg

instead:

/var/www/wordpress/wp-content/themes/theme-name/tmp/b0a1f733d586f7cdb7f47381a6b5efd6.jpg